From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 010E8C433ED for ; Fri, 16 Apr 2021 15:01:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCA0C611AC for ; Fri, 16 Apr 2021 15:01:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244804AbhDPPBa (ORCPT ); Fri, 16 Apr 2021 11:01:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:43216 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236384AbhDPPB1 (ORCPT ); Fri, 16 Apr 2021 11:01:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618585262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=h5MhNFa+G0GXPiMOp8zeJtDGBUydEX9X5pmRHMN7Eug=; b=XR/e+NTTTfwQ7jfhHBmwVOhMuPvL+4dR/AEzchWh2cw7pGaxVBgwFrM494YuMlztZ6PKTS q8SmLX0pQXA5JHSYfKXZBPECkxsMRORv4X0T5KdJGSbFjAV1et0hvpMF2jvZYn1Zu/I2KU D4swtJeoTfuAYk3bMQNJRhQpLGYUOXA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-600-Z4tRWluRNO-bDudkzhywfw-1; Fri, 16 Apr 2021 11:00:57 -0400 X-MC-Unique: Z4tRWluRNO-bDudkzhywfw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AC79B107AFB6; Fri, 16 Apr 2021 15:00:54 +0000 (UTC) Received: from [10.36.113.21] (ovpn-113-21.ams2.redhat.com [10.36.113.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 34752107D5C1; Fri, 16 Apr 2021 15:00:47 +0000 (UTC) Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs To: Jason Gunthorpe Cc: "Liu, Yi L" , Jean-Philippe Brucker , "Tian, Kevin" , Jacob Pan , LKML , Joerg Roedel , Lu Baolu , David Woodhouse , "iommu@lists.linux-foundation.org" , "cgroups@vger.kernel.org" , Tejun Heo , Li Zefan , Johannes Weiner , Jean-Philippe Brucker , Alex Williamson , Jonathan Corbet , "Raj, Ashok" , "Wu, Hao" , "Jiang, Dave" References: <20210401134236.GF1463678@nvidia.com> <20210401160337.GJ1463678@nvidia.com> <4bea6eb9-08ad-4b6b-1e0f-c97ece58a078@redhat.com> <20210415230732.GG1370958@nvidia.com> <20210416140524.GI1370958@nvidia.com> <20210416143451.GJ1370958@nvidia.com> From: Auger Eric Message-ID: <6159ef35-c24e-105f-43f6-f90d481f4b24@redhat.com> Date: Fri, 16 Apr 2021 17:00:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210416143451.GJ1370958@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jason, On 4/16/21 4:34 PM, Jason Gunthorpe wrote: > On Fri, Apr 16, 2021 at 04:26:19PM +0200, Auger Eric wrote: > >> This was largely done during several confs including plumber, KVM forum, >> for several years. Also API docs were shared on the ML. I don't remember >> any voice was raised at those moments. > > I don't think anyone objects to the high level ideas, but > implementation does matter. I don't think anyone presented "hey we > will tunnel an uAPI through VFIO to the IOMMU subsystem" - did they? At minimum https://events19.linuxfoundation.cn/wp-content/uploads/2017/11/Shared-Virtual-Memory-in-KVM_Yi-Liu.pdf But most obviously everything is documented in Documentation/userspace-api/iommu.rst where the VFIO tunneling is clearly stated ;-) But well let's work together to design a better and more elegant solution then. Thanks Eric > > Look at the fairly simple IMS situation, for example. This was > presented at plumbers too, and the slides were great - but the > implementation was too hacky. It required a major rework of the x86 > interrupt handling before it was OK. > > Jason >